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52 FLOAT SWITCH REPLACEMENT
1. Unscrew the screw located on the top edge of the upper
front panel and remove this panel.
2. Remove the lower top panel.
3. Unplug the Temp/Air/Float plug-in connector from its
connection box located on the RH side and behind the
control box.
4. Disconnect the wires from the terminal block. Refer to
Frame 15.
5. The rear panel (2nd down from the top) is held by 4
screws. Remove the screws and the panel to access the
float switch.
6. Remove the 2 screws and take off the saddle bracket.
7. Turn the hexagon nut anticlockwise to remove the
tension in the seal then withdraw the switch.
8. Fit the new switch, with the line mark at the bottom,
ensuring the float is able to fall from the horizontal - see
diagram.
53 BOILER CONTROL
WARNING
.
The ON/STANDBY [1/0] button does NOT electrically
isolate the boiler.
Before attempting any electrical fault finding ALWAYS carry out
the preliminary electrical system checks as detailed in the
Instructions for the British Gas Multimeter or other similar
commercially available meter.
The preliminary electrical system checks are the FIRST
electrical checks to be carried out during a fault finding
procedure.
On completion of any service/fault finding task which has
required the breaking and remaking of electrical connections
the following checks MUST be repeated:
a.
Earth continuity
b. Polarity
c.
Resistance to earth
Detailed instructions on the replacement of faulty components
are contained in the 'Servicing' section of these Installation &
Servicing Instructions.
GENERAL INFORMATION
If a flow switch is not connected to the boiler a link should be
fitted between the 2 terminals for the flow switch. If the
terminals are left disconnected the display will indicate "No
flow" and the boiler will not operate.
Anticycle will be in operation each time the boiler thermostat is
satisfied and a rapid demand for heat is required. The same
situation will occur if the external controls operate rapidly. This
feature reduces component wear and ensures continuous
troublefree operation. The anticycle duration is one to three
minutes.
If the system pump, with a maximum current of 3A, is
connected to the boiler pump terminals, pump overrun will be
in operation if the flow temperature is greater than 75
the heat demand is satisfied, and will continue to run until the
o
boiler flow is less than 75
o
than 75
C when the demand for heat is satisfied then the
pump will cease to operate.
Frost protection is inbuilt with the boiler. If the flow temperature
o
falls to approximately 3
C then the boiler will operate until the
Concord CXC -
Installation
FAULT FINDING
o
C, when
C. If the flow temperature is less
9. Replace the saddle bracket.
10. Run electrical leads through the clips and wire into the
plug-in connector.
11. Fit the
plug-in
connector
and
replace all
the panels.
flow temperature exceeds 4
is required the internal programmer should be set to 24 hours
under the programme status menu and an external
programmer and frost thermostat wired and connected to the
volt-free external control terminals on the boiler.
There is an option kit available with 2 sets of volt-free contacts.
One set of volt-free contacts is for 'Lockout' and 'Overheat'
combined, and one set of volt-free contacts is for 'Boiler run'.
There is an option kit available to enable temperature
compensation to be used. The outside temperature adjusts the
boiler flow temperature to satisfy the heating load and ensure
efficient boiler operation.
The gas valves operate on a High/Low and Off principle. At
start up, with the flow temperature less than 55
will start at low rate and after one to three minutes the high
rate gas valve will open. On reaching the set point, determined
by the user, the boiler will go to low rate and when the
temperature reaches the set point plus 3
valve will close. When the temperature falls 2
start at low rate and remain there until the temperature falls to
o
the set point less 2
C then the high rate gas valve will operate.
On start up the high rate gas valve will operate immediately
after detection if the boiler flow rate is greater than 55
In order to determine the continued correct operation of the
control every 4 hours the boiler will shut down for a maximum
of 30 seconds to do a self -check operation and restart
automatically.
The control will display the number of operational hours of the
boiler to the nearest hour and cannot be reset.
The boiler thermostat has a range of 60-80
o
with an accuracy of ± 2
C and hysteresis of 3
The full sequence control enables 5 attempts at ignition, with 1
minute intervals between attempts, followed by nonvolatile
lockout if detection does not take place.
If the [0/1] switch on the front panel is at 'Standby.....0' then the
pump will continue to run indefinitely. In this state the frost
protection can not operate.
In 'Lockout' the pump will continue to run only if the
temperature is greater than 75
be off.
FAULT FINDING
o
C. If an external frost thermostat
o
C, the boiler
o
C the low rate gas
o
C the boiler will
o
C.
o
o
C, in 1
C steps,
o
C.
o
C if it is less then the pump will
33
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